Linezolid is a synthetic antibiotic used for the treatment of serious infections caused by Gram-positive bacteria that are resistant to several other antibiotics. The empirical formula is C16H20FN3O4. Its molecular weight is 337.35, and its chemical structure is represented below:

The main indication of Linezolid is the treatment of severe infections caused by Gram-positive bacteria that are resistant to other antibiotics; it should not be used against bacteria that are sensitive to drugs with a narrower spectrum of activity, such as penicillins and cephalosporins. In both, the popular press and the scientific literature, Linezolid has been called a “reserve antibiotic”one that should be used sparingly so that it will remain effective as a drug of last resort against potentially intractable infections.
Linezolid Form III, was discovered and described in U.S. Pat. No. 7,714,128. The crystalline form III was characterized by an x-ray powder diffraction spectrum having peaks expressed as 2θ at about 7.6, 9.6, 13.6, 14.9, 18.2, 18.9, 21.2, 22.3, 25.6, 26.9, 27.9 and 29.9 degrees.
WO2012029074 discloses pharmaceutical composition of Linezolid Form III, polacrilin potassium as disintegrant and hydroxypropylmethyl cellulose as binder along with pharmaceutically acceptable ingredients, prepared by dry granulation, wherein the composition retains Linezolid in its original crystalline form.
US20070104785 discloses pharmaceutical dosage of Linezolid Form III, water-insoluble polymer or colloidal silicon dioxide or clay or carbon dioxide source as means to reduce the gelling tendency of Linezolid along with pharmaceutically acceptable excipeints. However, there still persists the problem of erratic dissolution of the Linezolid from the dosage form.
WO2010026597 discloses a multiparticulate composition comprising a core in the form of beadlet or pellet, manufacture by extrusion and spheronization method, the core comprises Linezolid form III, one or more binders, and one or more disintegrants. Both processes require either special material or equipment which are not desirable for commercial production.
WO2007102082 assigned to Glenmark Pharmaceuticals Ltd discloses compositions of Linezolid crystalline Form II containing lactose-based water soluble excipient.
Linezolid Form III exhibits a gelling tendency when it comes into contact with water, which eventually leads to erratic dissolution of the Linezolid from the dosage form. Hence, there is a need to develop solid dosage forms of Linezolid Form III, which provides consistent dissolution profile.
The inventors of the present invention have used Soy Polysaccharides which exhibits excellent disintegration and improved dissolution characteristics of Linezolid Form III i.e. significantly reduces gelling tendency of Linezolid Form III. Its use in soluble systems has evidenced fast and efficient disintegration of oral dosage forms prepared with a varying range of hardness values.
Soy Polysaccharides is an all-natural, soft white to light-tan powder, which does not contain starch or sugar. It is derived from dehulled and defatted soybean flakes by a special process.